Biosensors make use of the interaction of biological molecules (biomolecules) as a means of sensing an external environment. Biosensors can be very selective, due to the highly specific interactions between biomolecules, for example antibodies and their antigens, cytokines and their cell-surface receptors, enzymes and their substrates, or nucleic acids with themselves or other molecules. The species being sensed in the environment is referred to as the analyte. Therefore, the analyte can be another biological molecule or a chemical that interacts with an immobilized chemical or biological (chem/bio) recognition molecule that has high selectivity for the target analyte. Further, signal transduction methods combined with amplification can provide biosensors with high sensitivity. These properties—selectivity and sensitivity—make biosensors particularly attractive as analytical devices.
A biosensor preferably can analyze multiple analytes simultaneously. Therefore, microarray technology has become an important tool for high throughput analysis of biological systems. See A. Kozarova et al., J. Proteome Res. 5, 1051 (2006); and J. Sobek et al., Comb. Chem. High T. Sci. 9, 365 (2006). The ability to selectively modify electrode surfaces of a microarray is a critical component in the development of bioelectronics, proteomic research, tissue engineering, clinical diagnostics, and chemical and biological sensing. Multi-analyte sensors require surface chemistries that are robust and allow for addressable functionalization with peptides, nucleic acids, proteins, and sensitive chemical groups onto closely spaced arrays. See I. Medintz, Nature Mat. 5, 842 (2006); and C. Y. Fan et al., Nano Lett. (2006).
Therefore, a need remains for a versatile surface chemistry capable of selective functionalization of an electrode array with controllable surface density, and which is compatible with chem/bio recognition element immobilization. Such chemistry would facilitate development and fabrication of complex surfaces allowing precise manipulation, detection, and quantification of chemical and biological compounds.